The present report was prepared in response to General Assembly resolution 64/205, in which the Assembly requested the Secretary-General to report to it at its sixty-sixth session on the status of sustainable development in mountain regions. The report describes the status of sustainable mountain development at the national and international levels, including an overall analysis of the challenges that lie ahead, and provides suggestions for consideration by the Assembly as to how to continue to promote and effectively sustain development in mountain regions around the world within the existing policy context, including chapter 13 of Agenda 21, the Plan of Implementation of the World Summit on Sustainable Development (“Johannesburg Plan of Implementation”), the Millennium Development Goals, and the upcoming United Conference on Sustainable Development.